the importance of pinching out

Pinching out the main stem of a plant activates and encourages the growth of its auxiliary buds, resulting in a bushier plant.

The four marigolds, below, were pinched out a couple of weeks ago. They used to be distinctly four separate plants growing straight up, but now it's grown to be a bush of almost-flowering marigolds with lots of side stems. Those buds look ready to open, any morning now. 

*edited* This is what they look like a couple of weeks later: